Three levels dated February 1997. I always turn around and press the wall when I start these old maps, because a lot of them had secrets right behind the start location; and that is how I finished E1M1 in three seconds on my first go. E1M2 is a poor-quality deathmatch arena with a hidden exit five seconds from the start location (although you need to cheat to find it). E1M3 is larger, with 200+ baddies, but it's a boring undetailed dungeon of relentless tedium.